Poland's president Lech Kaczynski looked set to sign the EU's Lisbon treaty within days of Irish approval, and Czech counterpart Vaclav Klaus was not expected to delay for more than a few weeks, politicians said today.

Irish voters backed the treaty in yesterday's referendum, government and opposition officials said as vote counting continued today.

Kaczynski is expected to add his signature to the pact, aimed at streamlining the 27-nation bloc and giving it more clout, soon after confirmation of a "Yes" vote in Ireland.

"The moment Mr. President knows the final and official results, he signs it immediately," said Pawel Wypych, a minister at Kaczynski's chancellery. "It won't happen over this weekend, but it's a matter of days."

Klaus, who sees the document as a step toward a European superstate where national states will lose sovereignty, has not revealed his strategy but he is likely to yield eventually, political observers say.

Both houses of the Czech parliament have approved the treaty but a group of pro-Klaus lawmakers challenged the treaty at the Constitutional Court on Tuesday, halting the process for weeks at least. The court is widely expected to dismiss the challenge.

Klaus cannot legally sign the treaty before the ruling and he is seen bending under pressure from home and abroad and sign, said Alexandr Vondra, former Czech deputy prime minister for Europe during the Czech EU presidency earlier this year.

"In case the Constitutional Court does not uphold the complaint, he will respect the political and constitutional reality and sign," Vondra told Reuters.

"I believe (he will sign) soon after the court verdict."

The Czechs will come under pressure form other EU countries to ratify the document fast to allow the EU to start operating under the new rules from the beginning of 2010. Britain's Conservative leader David Cameron, whose party leads opinion polls, has said he would hold a referendum on Lisbon if it is not ratified in all EU states before an election expected by May 2010, and Klaus could keep the door open.

But Stefan Fuele, the current Czech minister for Europe, said Klaus would not hold out for that long.

"I am convinced that President Vaclav Klaus ... would not tie up the ratification of the Lisbon Treaty in the Czech Republic with the wishes of any other member state," he said.